Fall Bright has been providing winemaking supplies, grapes, juices (plus brewing supplies) for  amateur winemakers for over 20 years.  
An old grape packing house provides a home for Fall Bright.     

Fall Bright, The Winemakers Shoppe, 10110 Hyatt Hill, Dundee, NY 14837
607-292-3995 

                                                                  

This material is used in the treatment of wines with hydrogen sulfide. Such wines have a characteristic " rotten egg" smell.  This treatment should only be used when less drastic steps are not effective.  Hydrogen sulfide should be removed as quickly as possible after fermentation has stopped so that mercaptans are not produced in large quantities.  

 

Bocksin:  Silicium Dioxide  SiO2
Silicon (English) Dioxide
Silicium (Latin) Dioxide

 

Treatment for hydrogen sulfide: 
Bocksin (FROM the label): "is a solution of Silicium Dioxide for treatment of hydrogen sulfide odors and related off-flavors in wine. Usage is 15 ml per ten liters (2.75 gallons). Stir thoroughly and wait 24 hours. Rack without disturbing the sediment. It is recommended to filter the wine after treatment. If the wine becomes cloudy, treat with finings." 

20 ml plastics syringe are available for sale to aid in dispensing this product. 

1 USA gallon is 3.84 liters, 1 teaspoon is 5 ml, regarding the above text that 10 liters is 2.75 gallons is a rough figure with rounding off factors, I get 2.6 gallons per 10 liters. Anyway we would treat 5 US gallons with 30 ml or 6 teaspoons or 2 tablespoons of Bocksin.

We would express the instructions to rack without disturbing the sediment.  If the wine becomes cloudy, treat with finings or filter if desired or instead of fining.  . 

So What is Silicium Dioxide?  http://www.vanderkrogt.net/elements/elem/si.html 
Silica, Silicium Dioxide, Silicion Dioxide
This link would have been great in chemistry class!  I did not copy it nor did I request permission to do so, but do check it out.  Our winemakers are worried about toxic chemicals for use and I feel safe with this item.  Read your grocery item labels in the spice department and you will find that you eat this item!  Marcy